1. Field of the Invention
The present invention relates to a device for varying an equivalent inertia moment of an engine flywheel of a vehicle with a manual transmission, thereby reducing variations in engine speed during idling and improving response characteristics during normal running.
2. Description of the Related Arts
The flywheel of an engine suppresses speed variations due to its particularly large inertia moment as compared with other rotatable parts of the engine. When the inertia moment of the flywheel is set large, vibrations due to speed variations can be reduced at low engine speeds. The flywheel, with its large inertia moment, serves to decrease transmission gear chattering due to speed variations during idling when the transmission is in neutral and the clutch is engaged. Further, when the inertia effect is large, the idling speed can be set low to improve.
However, when a car is running at normal speeds, the inertia moment of the flywheel is not needed to be set as large as during idling due to the inertia of the vehicle itself and the moment inertia of its drive system. As a result, the flywheel carries an extra mass during normal running. In high performance applications, a large inertia moment of the flywheel is actually harmful, because it deteriorates engine response.
In the prior art, it has been impossible to satisfy at the same time the contradictory requirements for low speed stability and for quick engine response. It has been a common practice to set the inertia moment of the flywheel and idling speed at such appropriate values that chattering of the transmission and deterioration of fuel economy due to speed variations can be held within tolerable limits. It has been impossible to vary an equivalent inertia moment of the flywheel.
Japanese Patent Publication SHO No. 53-117167 discloses a flywheel comprising a flywheel main body fixed to a rotating shaft, a weighting means freely displasable in a radial direction of the flywheel main body, an auxiliary rotating means rotatably and loosely fit around the rotating shaft and a spring fixed to the flywheel main body and pressing the weighting means elastically against the auxiliary rotating means. In such a flywheel, through balance between a centrifugal force acting on the weighting means and an urging force by the spring, a large inertia moment of the flywheel can be assured at high speeds and a small inertia moment of the flywheel can be assured at low speeds. However, due to such a device for varying an inertia moment of a flywheel, a large adjustment of an inertia moment of a flywheel can not be expected, because a mass of the weight means is small as compared with a mass of the flywheel main body.